It is highly unlikely whatever violence you're writing about hasn't been written before or been featured on television before. You cannot cripple your own efforts for the fear that some unhinged individual might emulate it on some level to satisfy their own ends. I mean, that's even if you did hit those odd-end variables of getting a reader who got that far gone and opted to emulate your fiction rather than any other they might be exposed to.
When those killers emulated Dexter Morgan, they weren't going by the books.
I'd say this isn't something worth worrying about. Care about producing quality content rather than the moon-shot chance that someone is going to kill/rape/steal in a way similar to your works. The media would be far more likely to blame video games on the perpetrators shelves than anything so small as a comic in their browser history.
I feel that's entering into some dangerous territory. I think the Fargo mini-series did it quite well, in almost that exact scenario. We do have a guy who does strike his wife, and his wife has pretty much belittled and abused him verbally to the point that we want to be happy he did this. But it is presented with this degree of distance, and it becomes disgusting; especially as we see the fallout of this and the lengths the character goes through to keep up the ruse. I think presenting a more balanced, or at least, a less strawman scenario, especially when there is going to be some nasty consequences, is important.
Whether or not the reader is okay with the results is on them. A good story should be able to make you feel conflicted. And not in a forced way like "But my evil would stop a greater evil, now that's on you" way; but rather a "I can see how someone in this walk of life could reach this moral event horizon and choose poorly in order to stop feeling the pain, even if it meant hurting others." We don't need to love our villains, but unless they were born slithering out the razor-trap of Satan's anus; they're generally still people with wants and needs which may be perverted or controlled in order to get them to do these bad things.
I guess in short; don't worry about some nutjob doing something based on what you wrote/drew. The odds are against you anyway, so you may as well enjoy the unfettered freedom.